Properties and Decomposition Behaviors of Reactively Sputtered Pt(O) Electrode Materials
- PDF / 581,749 Bytes
- 9 Pages / 420.48 x 639 pts Page_size
- 85 Downloads / 201 Views
suggested that oxygen-containing Pt(O) electrodes might be superior to electrodes of conventional Pt deposited without the deliberate incorporation of oxygen. Pt(O) top electrodes deposited by sputtering Pt in an oxygen-containing ambient were found to reduce the need for oxygen annealing after top electrode deposition [I], and oxygen-containing Pt bottom electrodes were found to prevent the increase in leakage usually seen in Pt/(Ba,Sr)TiO 3/Pt capacitors after anneals in H 2-containing ambients [2]. Additional interest in oxygen-containing Pt and the platinum oxides PtOx as electrode materials for FE applications stems from observations that both PtO [3] and other noble metal oxide electrodes [4,5] can improve the endurance properties of the ferroelectric Pb(Zr,Ti)0 3 (PZT). Several groups have described Pt(O) and PtOx films prepared by reactive sputtering of Pt in Ar/0 2 mixtures [6-10]. While the various composition and microstructure regimes of the Pt(O)-PtOx family are also described in the present work, the focus here is on the thermal stability and oxygen-loss characteristics of these Pt(O)-PtOx films at the temperatures of HE/FE deposition and processing (400 - 650 0 C). Our experiments were motivated by the concern that easily decomposable Pt(O) electrode materials might lose most of their oxygen before HE/FE
57
Mat. Res. Soc. Symp. Proc. Vol. 596 © 2000 Materials Research Society
deposition could be completed, and by the hope that a detailed understanding of Pt(O) oxygen loss behaviors would be useful in optimizing these materials for HE/FE electrode applications. This study investigates Pt(O)-PtOx films with x in the range 0 to -1.4. Composition and microstructure regimes are identified, and film oxygen and properties (adhesion, roughness and stress) are examined as a function of deposition conditions and post-deposition annealing history. EXPERIMENT About 20-30 Pt(O) films having thicknesses in the range 100 to 300 nm were deposited on thermally oxidized silicon substrates by reactive sputtering in an Endura platform dc magnetron system containing a 30 cm diam Pt target. Two sets of deposition conditions were used: high power (1000 W) and low power (125 W). The high power (HP) conditions utilized an Ar/0 2 sputter gas with a total pressure of -5-7 mTorr, with Ar flow kept constant at 10 sccm and 02 flow varied from 0% to 75%. Substrate temperature was ambient (- 30 °C, RT) or 350 °C. The
low power (LP) conditions utilized an Ar/0 2 sputter gas having a total pressure of -10-12 mTorr, with 02 partial pressure varied from 0% to 15%; substrate temperature was 300 0C. Deposition rates for pure (0-free) Pt were -190 nm/min for the HP conditions and -26 nm/min for the LP conditions. After deposition, the Pt(O) films were subjected to various rapid thermal anneals (RTA) in an AG Associates Heatpulse system. Anneals were performed in an atmospheric pressure ambient of N 2 or 0, using a ramp rate of 35°C/s; typical time at temperature was 5 min at 650'C. Pt(O) samples were characterized before and after an
Data Loading...
